On the relative roles of elevated heating and surface temperature
gradients in
driving anomalous surface winds over tropical oceans
Abstract
Elevated heating by cumulus convection, and sea surface temperature gradients, are both thought to contribute towards surface winds over
tropical oceans. We examine relative strength and role of each mechanism by imposing forcing derived from data on a linear primitive
equation model with idealized parameterizations for the two forcings, and comparing the response with observed surface winds. Two test
cases are studied: one related to the El Niņo-Southern Oscillation, and the other related to the 'dipole' mode in the tropical Atlantic.
We find that in both cases, elevated heating dominates the surface zonal wind response, and contributes significantly to the meridional
wind response, especially in the subtropics and the South Pacific and South Atlantic Convergence Zone regions. Surface temperature
gradients dominate the meridional wind forcing in regions near the
equator with strong meridional temperature gradients.
Send preprint requests to jchiang@ldeo.columbia.edu